Rill Erosion Assessment in Cultivated Lands and Farmers Perception on Soil Erosion, A Case of Delbo Wogene Micro-Watershed Southern Ethiopia

摘要

Land degradation in the form of soil erosion is a major constraint to farming activities and sustainable agricultural development in Ethiopia. Sophisticated methods of erosion measurements are expensive, time consuming and requiring highly trained manpower. However, simple field methods also could give adequate and reliable information such as field method of rill assessment. Most soil and water conservation planning approaches rely on empirical assessment methods and hardly consider farmers’ knowledge of soil erosion processes. Therefore, this study was aimed at assessing the magnitude and rate of rill erosion and to evaluate the farmers’ perception about erosion control practices, causes of soil erosion; constraints of soil and water conservation practices and identify local erosion indicators based on farmers’ knowledge and assess relevance of these indicators in estimating soil erosion damage. The Delbo Wogene watershed in which the study conducted was located in Wolaita Zone, Southern Ethiopia. This study presents rill assessment through survey methodology and farmers’ perception. Social survey data were assessed based on descriptive statistics. To quantify the amount of soil loss due to rill erosion, each rill’s dimensions were carefully sectioned and measured to determine the volume and rates of soil erosion. The average total volume of soil loss due to rill erosion was 26.8m3 which is equivalent to 27.8 t ha-1. The average total rate of soil loss from both rill and inter-rill erosion in the study area was 35.75 t ha-1. The mean total soil loss estimated using USLE resulted 48.6t ha-1 years from twelve cultivated fields at the upper, middle and lower zones of the study catchment. The HH survey results reveal that 73% of the farmers in the study catchment were aware of the problem of rill erosion feature and believed its severity. Lack of vegetation cover and excessive rainfalls were ranked first, 65% and 61% and 48% of respondents were ranked broken SWC for second as major causes of soil erosion respectively. The overall outcome from the research showed that unless appropriate interventions taken in the study area, reversing the soil erosion process would become difficult for the future. Based on the outcome, land management practices such as agro-forestry systems, conservation tillage, crop rotations and site-suitable SWC structures and crop rotations should be practiced in the study area with a full consensus and participation of the dwellers by giving attention to keep the standards of physical structures. Keywords: Rill erosion, soil loss, Farmers perception, Erosion indicators, SWC, Delbo Wogene, Southern Ethiopia